Add check that task provides all results it should

Value returned from execute method of task should contain all
results that are mappend with task.rebind. To verify that we
check that the value can be indexed with all necessary indexes.
If that fails, we put warning to log.

Change-Id: I21aac7b36885668155c2d7bd2eedcf4eeba22b11
Merge "Add check that task provides all results it should"